A review from August 14th comments on the lack of challenge of the AI. Can anyone comment?
Can a hard mode in the campaign present any challenge? I like AOW/Triumph, so I'd be willing to buy the game at it's starting price, but I don't think I'm going to bother playing it on easy mode.

They came out with a patch fairly quickly, but I don't see any mention of the AI.
Patches came out with the AOW3 expansions that improved the AI, and I was very pleased with the hard mode of the Frostling campaign (I've yet to play the earlier halfling campaign) which for me added replayability from failing and then to do better. I can say the same thing for the optional hard modes of the earlier games, when I was more of a noob at any rate.

I fully expect that a harder AI difficulty will be implemented.

As usual, it really depends on how good a player you are. There are routine "AI is too hard even on very easy" and "AI is too easy even on very hard" complaints alongside one another on various forums.

The one issue that does seem to exist is that the AI will begin to turtle to an unreasonable degree in very long running maps, though this is obviously more likely to come up with huge maps than with small ones.